Those Daniel Defense Omega are pretty good, I have a similar DD EZ CAR M4 7.0 drop-in rails on one of my AR and fits great, no movement, but unfortunately they don't make them anymore.
Look at AR15.com Equipment Exchange parts and accessories section, that's where I bought my Knight's Armament Co. M4 RAS rails a long time ago.
If you don't mind to substitute a lesser cost brand try to look for the P&S M4 RAS, looks the same as the Knight's Armament RAS and they also supply the US military.
Here's my Colt M4 clone model SP6920 marked "Sporter M4 Carbine", I went with the Navy/ USMC style with the LMT (Lewis Machine & Tool) rear sight, Aimpoint CompM2 M68, Knight's Armament M4 RAS rails & forward vertical grip and Surefire M951 weaponlight, (see my picture attachment below).